From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC] CPU hard limits Date: Fri, 05 Jun 2009 09:03:37 +0300 Message-ID: <4A28B539.3050001@redhat.com> References: <20090604053649.GA3701@in.ibm.com> <4A27BBCA.5020606@redhat.com> <20090605030309.GA3872@in.ibm.com> <4A28921C.6010802@redhat.com> <661de9470906042137u603e2997n80c270bf7f6191ad@mail.gmail.com> <4A28A2AB.3060108@redhat.com> <20090605044946.GA11755@balbir.in.ibm.com> <20090605051050.GB11755@balbir.in.ibm.com> <4A28AB67.7040800@redhat.com> <20090605052755.GE11755@balbir.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: bharata@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, Dhaval Giani , Vaidyanathan Srinivasan , Gautham R Shenoy , Srivatsa Vaddagiri , Ingo Molnar , Peter Zijlstra , Pavel Emelyanov , kvm@vger.kernel.org, Linux Containers , Herbert Poetzl To: balbir@linux.vnet.ibm.com Return-path: Received: from mx2.redhat.com ([66.187.237.31]:45423 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750768AbZFEGFm (ORCPT ); Fri, 5 Jun 2009 02:05:42 -0400 In-Reply-To: <20090605052755.GE11755@balbir.in.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: Balbir Singh wrote: >> I think so. Given guarantees G1..Gn (0 <= Gi <= 1; sum(Gi) <= 1), and a >> cpu hog running in each group, how would the algorithm divide resources? >> >> > > As per the matrix calculation, but as soon as we reach an idle point, > we redistribute the b/w and start a new quantum so to speak, where all > groups are charged up to their hard limits. > > For your question, if there is a CPU hog running, it would be as per > the matrix calculation, since the system has no idle point during the > bandwidth period. > So the groups with guarantees get a priority boost. That's not a good side effect. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.